Solenoid valve for a slip-regulated hydraulic brake system of a vehicle

ABSTRACT

A rod-shaped solenoid valve that is provided for insertion into a receiving bore of a hydraulic block of an antilock hydraulic brake system of a vehicle, wherein a fluid influx takes place through an axial bore of a valve seat part that is inserted into a valve support. For simple sealing, a plastic end piece is placed onto the end of the valve support that prodrudes into the receiving bore and seals the valve support in relation to the receiving bore and also seals the valve seat part.

PRIOR ART

The invention is based on a solenoid valve, which is provided forinsertion into a receiving bore in a hydraulic block of a slip-regulatedhydraulic brake system of a vehicle. It is in particular provided as aninlet valve preceding a wheel brake cylinder or as a reversing valveconnected between the master cylinder and the rest of the vehicle brakesystem.

A valve of this kind has been disclosed by DE 44 12 648. This valve isembodied as rod-shaped and has a rotationally symmetrical valve supportwith an axial through bore. For the purpose of a hydraulic connection,the valve support is provided for insertion into a receiving bore of ahydraulic block so that an inlet on an end face of the valve support andan outlet on the circumference of the valve support communicate withfluid conduits of the hydraulic block, which feed into the receivingbore in a bottom face or on the circumference.

The valve support protrudes with a part of its length out of thehydraulic block. A valve dome is attached to the protruding end face andreceives an armature so that it can move axially. In order to actuate anaxially movable valve closing body, a valve tappet is affixed to thearmature and protrudes into the through bore of the valve support. Forthe purpose of electromagnetic actuation, a coil is slid onto the valvedome that protrudes from the hydraulic block.

The valve support is sealed in the hydraulic block by means of twoO-rings, which makes manufacture and assembly of the known solenoidvalve relatively costly since O-ring grooves have to be let into thevalve support and the O-rings must be inserted into the O-ring groovesbefore the insertion of the solenoid valve into the hydraulic block.

ADVANTAGES OF THE INVENTION

In the solenoid valve according to the invention, with the features ofclaim 1, an end piece made of plastic is affixed to the end face of thevalve support to be inserted into the receiving bore in the hydraulicblock and this end piece seals the valve support at the bottom of thereceiving bore in relation to the hydraulic block and thus hydraulicallyseparates from one another fluid conduits of the hydraulic block thatfeed into the receiving bore in the bottom face and those that feed intothis bore on the circumference. The manufacture of the solenoid valveaccording to the invention is simplified by means of the end piece madeof plastic in comparison to a seal for example by means of an O-ring,since no O-ring groove has to be produced on the valve support.Likewise, the assembly is simplified in comparison to a conventionalO-ring seal by means of caulking or using the self-clinch technique.

Advantageous embodiments and improvements of the invention disclosed inclaim 1 are the subject of the dependent claims.

The sealing with the plastic end: piece according to claim 3 isparticularly advantageous and this end piece both seals the valvesupport in the receiving bore and rests in a sealed fashion against thevalve seat part, i.e. hydraulically separates its bore from the valveoutlet.

Preferably, the seals according to claims 2 and 3 are disposed on theend piece so that with the application of pressure through brake fluid,they are more strongly pressed on, so that they seal reliably evenstress of the seals as a result of material ageing or temperatureinfluences.

According to claim 4, the end piece seals the valve support against thehydraulic block also at the mouth of the receiving bore, i.e. inrelation to the outside. This has the advantage that an additionalsealing element or a fluid-tight caulking of the valve support in thehydraulic block is not required.

According to claim 5, a check valve is integrated into the end piece,which produces a return flow function in a simple manner, in whichotherwise requires a separate check valve or an expensive and wear-pronethe sealing collar that permits a through flow in one direction, in lieuof the end piece.

A valve support produced according to claim 9 by means of extrusion, inparticular cold extrusion, has the advantage that it can be producedrapidly and cheaply. This furthermore has the advantage that aninexpensive forming steel can be used for the valve support, whichbrings with it the property of a favorable capacity for being welded.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail below in conjunction withtwo exemplary embodiments represented in the drawings.

The two FIGS. 1 and 2 show an axial section through two differentembodiments of a solenoid valve.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The rod-shaped solenoid valve 10 according to the invention depicted inFIG. 1 has a rotationally symmetrical valve support 14, which isprovided with an axial through bore 12 and has a fastening flange 16that is an integral part of the valve support and is disposedapproximately in the middle of its length. The valve support 14 isinserted into a receiving bore 18 in a hydraulic block 20 and is securedby caulking on its fastening flange 16. A hydraulic part 34 of thesolenoid valve 10 is disposed in the hydraulic block 20, a magnetic part22 protrudes from the hydraulic block 20. The valve support 14 is anextruded part that is produced in one work cycle and does not haveundercuts.

On an end face of the valve support 14 remote from the hydraulic block20, the magnetic part 22 has an axially movable armature 24 contained ina valve dome 26, which is welded to the valve support 14 in a fluidtight manner. A valve tappet 28 extends from the armature 24 into thethrough bore 12 of the valve support 14, whose end remote from thearmature 24 is embodied as a valve closing body 30 in the shape of ahalf ball. A coil 32 is slid onto the valve dome 26.

The hydraulic part 34 of the solenoid valve 10 according to theinvention includes a cylindrical valve seat part 36, which is pressedinto the through bore 12 of the valve support 14 from an end facedisposed in the receiving bore 18. The valve seat part 36 has an axialbore 38 passing through it, which feeds into a conical valve seat 40 onthe end face of the valve seat part 36 oriented toward the valve tappet28. A helical compression spring 42 is disposed between the valve seatpart 36 and the valve tappet 28, and this spring presses the valvetappet 28 away from the valve seat part 36 and consequently lifts thevalve closing body 30 up from the valve seat 40; the solenoid valve 10is therefore open in its normal position when it is without power.Through supplying power to the coil 32, the armature 24 is attracted tothe end face of the valve support 14 oriented toward it, i.e. thearmature 24 moves together with the valve tappet 28 in the direction ofthe valve seat body 36 so that the valve closing body 30 is pressedagainst the valve seat 40 and the solenoid valve 10 is closed. A valvestroke is adjusted by means of the depth to which the valve seat part 36is pressed into the through bore 12 of the valve support 14.

Axially parallel outflow conduits 44 lead along an outer circumferenceof the valve seat part 36 to the end face of the valve support 14disposed in the receiving bore 18. In the exemplary embodiment depicted,the solenoid valve 10 according to the invention has three outflowconduits 44 that have round cross sections and are disposed evenlydistributed over the circumference. The outflow conduits 44 are let intoa wall of the through bore 12, i.e. in the valve support 14.

A cup-shaped end piece 46 is slid onto the end of the valve support 14that is inserted into the receiving bore 18. The end piece 46 iscomprised of a thermoplastic plastic to which approximately 20% carbonfibers are added as a filler. It is an injection-molded part. Apinshaped projection 48 that is of one piece with the end piece 46protrudes from the inside of a bottom of the end piece 46 and engages inthe axial bore 38 of the valve seat part 36. The end piece 46 has threeseals that are of one piece with it, the first seal 50 and third seal 52are embodied extending around the outer circumference and produce a sealagainst a circumference wall of the receiving bore 18 in the vicinity ofa bore bottom and beneath the fastening flange 16 of the valve support14. The second seal 54 is produced by the projection 48 that fits in asealed fashion in the axial bore 38 of the valve seat part 36. The threeseals 50, 52, 54 rest with low pressure. At least the first and secondseals 50, 54 are acted on from the inside with fluid, i.e. they arepressed more tightly with increasing pressure and as a result, reliablyseal even at high pressure and with high pressure differences.

The end piece 46, including its projection 48, has an axial bore 56passing through it that constitutes an opening and has a throttlelocation 58.

A filter element 60 is attached to the bottom of the end piece 46 fromthe outside, which is comprised of a plastic injection-molded part 60,which is injection molded around a plate-shaped filter screen 62. Thefilter element 60 has three support feet 64 that rest on the bottom ofthe receiving bore 18 of the hydraulic block 20 and thereby hold the endpiece 46 on the valve support 14.

On the end face of the valve support 14 that protrudes into thereceiving bore 18, the outflow conduits 44 feed into an annulardisk-shaped hollow space 66 that is bordered by the bottom of the endpiece 46 and the end face of the valve support 14 and the valve seatpart 36 which end face is enclosed by the end piece 46 and disposed inthe receiving bore 18 of the hydraulic block 20. Three radial conduits68 extend outward in a star shape from the hollow chamber 66, whichcommunicate with three openings 70 in a circumference wall 71 of the endpiece 46, the circumference wall encompasses the valve support 14. Ahollow cylindrical filter screen 72 is injection molded in thecircumference wall 71 of the end piece 46 and covers the openings 70.

A check valve is disposed in the bottom of the end piece 46, which valveis comprised of an axially parallel bore 74 that widens out with aconical step toward the bottom of the receiving bore 18 and a ball isinserted into this bore as a valve body 76. The valve body 76 is securedin the bore 74 by the filter element 60.

The hydraulic connection of the solenoid valve 10 according to theinvention to an antilock vehicle brake system is symbolically depictedin FIG. 1: the solenoid valve 10 according to the invention is connectedin a main brake line 78 that leads from a master cylinder 80 to a wheelbrake cylinder 82; it serves as an inlet valve of the wheel brakecylinder 82. The master cylinder 80 thus communicates with the axialbore 38 in the valve seat part 36 by way of a fluid conduit 84 thatfeeds axially in the bottom of the receiving bore 18. The wheel brakecylinder 82 is connected to a radial fluid conduit 86 that feeds in thecircumference of the receiving bore 18, i.e. by means of the openings 70and the radial conduits 68 of the end piece 46, the wheel brake cylinder82 communicates with the outflow conduits 44 that lead along the outercircumference of the valve seat part 36. The check valve 74, 76 isembodied as a bypass valve that permit fluid to flow through in thedirection from the wheel brake cylinder 82 to the master cylinder 80.

Parallel to the solenoid valve 10, an outlet control valve 88 and areturn feed pump 90 are connected in a return line 92 that leads fromthe wheel brake cylinder 82 to the master cylinder 78. A reservoir 94 isconnected to the return line 92 between the outlet valve 88 and thereturn feed pump 90. The brake slip regulation occurs in a manner thatis known in and of itself through brake pressure modulation by means ofthe solenoid valve 10, which serves as an inlet valve, and by means ofthe outlet valve 88 and the return feed pump 90.

In the modified embodiment of the solenoid valve 10 according to theinvention that is depicted in FIG. 2, a valve seat part 96 is embodiedas a stepped, cup-shaped deep-draw part made of sheet metal. It hasthree axially parallel bores 98 that are let into an annular step 100 ofthe valve seat part 96 and are distributed evenly over thecircumference. These bores 98 replace the outflow conduits 44 in thethrough bore 12 of the valve support 14 of the embodiment of theinvention depicted in FIG. 1. Otherwise, the solenoid valve 10 depictedin FIG. 2 is embodied identically to and functions in the same manner asthe solenoid valve 10 depicted in FIG. 1. To avoid repetition,references will be made to the embodiments in FIG. 1.

The foregoing relates to preferred exemplary embodiments of theinvention, it being understood that other variants and embodimentsthereof are possible within the spirit and scope of the invention, thelatter being defined by the appended claims.

What is claimed is:
 1. A solenoid valve (10) for insertion into areceiving bore (18) of a hydraulic block (20) of an antilock hydraulicbrake system of a vehicle, an extruded part valve support (14) that hasa through bore (12) and can be inserted into the receiving bore (18) ofthe hydraulic block (20), a valve dome (26) attached to the valvesupport (14) coaxial to the through bore (12), in said dome an armature(24) is received so that the armature can move axially and said dome isencompassed by a coil (32), a valve tappet (28) for actuating an axiallymovable valve closing body (30) that is disposed on the armature (24)and protrudes into the through bore (12) of the valve support (14), avalve seat part (36, 96) which, on an end face remote from the armature(24), is inserted into the through bore (12) of the valve support (14)and which has a bore (38) that leads from the end face remote from thearmature (24) to a valve seat (40) of the valve seat part (36, 96), afilter-equipped, cup-shaped end piece (46) made of rigid plastic isattached to the end of the valve support (14) remote from the armature(24) and encompasses the valve support (14) on the end and on thecircumference and has an opening (56) that leads from the end face ofthe end piece (46) remote from the armature to the bore (38) of thevalve seat part (36), said end piece includes three seals (50, 52, 54)that are embodied as being of one piece with the end piece (46), thefirst seal (50), in order to seal the valve support (14), rests againstthe bottom of the receiving bore (18) in the hydraulic block (20), thesecond seal (54) rests in a sealed fashion against the valve seat part(36), and the third seal (52), in order to seal the valve support (14)in the region of a mouth of the receiving bore (18) rests against thehydraulic block (20).
 2. The solenoid valve according to claim 1, inwhich the first seal (50) and the third seal (52) are embodied extendingaround an outer circumference of the end piece (46) and spaced apartfrom the end piece axially.
 3. The solenoid valve according to claim 1,in which the end piece (46) has a pin-shaped projection (48) of onepiece with it, said pin shaped projection engages in the bore (38) ofthe valve seat part (36), is passed through by the opening (56) of theend piece (46), and fits in sealed fashion in the bore (38) of the valveseat part (36).
 4. The solenoid valve according to claim 1, in which theend piece (46) has a check valve (74, 76).
 5. The solenoid valveaccording to claim 1, in which the valve seat part (96) is a deep-drawpart made of sheet metal.
 6. The solenoid valve according to claim 1, inwhich the valve seat part (36) is comprised of plastic.
 7. The solenoidvalve according to claim 1, in which the opening (56) of the end piece(46) has a throttle (58).
 8. The solenoid valve according to claim 2, inwhich the end piece (46) has a pin-shaped projection (48) of one piecewith it, said pin shaped projection engages in the bore (38) of thevalve seat part (36), is passed through by the opening (56) of the endpiece (46), and fits in sealed fashion in the bore (38) of the valveseat part (36).